Preheat the oven to 425°F (220°C).
Arrange the eggplant slices in a single layer on a baking sheet. Brush both sides with olive oil and season with ½ teaspoon salt and ½ teaspoon black pepper.
Roast for 15 minutes, or until the eggplant softens slightly. Remove from the oven and set aside.
In a large skillet over medium-high heat, add the ground pork, red onion, green bell pepper, garlic, oregano, basil, red pepper flakes, and the remaining salt and black pepper. Cook for about 10 minutes, stirring occasionally, until the meat is fully browned.
Add the water and continue cooking for 5 minutes, allowing the mixture to reduce slightly.
Reserve ½ cup of the tomato sauce. Add the remaining sauce to the skillet, stir well, and let simmer over medium heat for 10 to 15 minutes, or until the sauce thickens. Remove from heat.
Spread the reserved tomato sauce on the bottom of the baking dish. Add a layer of eggplant, followed by a layer of meat sauce and ½ cup of cheese.
Repeat the layering process with eggplant, meat sauce, and another ½ cup of cheese.
Add a final layer of eggplant on top and finish with the remaining cheese.
Bake for 10 to 15 minutes, or until the cheese is melted and golden around the edges.
Let rest for a few minutes before serving. Serve warm.